<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>display:flex+margin:auto</title>
	</head>
	<style>
		.box {
			display: flex;
			height: 100vh;
		}

		.item-box {
			width: 100px;
			height: 100px;
			background-color: pink;
			margin: auto;
		}
	</style>
	<body>
		<div class="box">
			<div class="item-box"></div>
		</div>
	</body>
</html>

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	<head>
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